SE538130C2

SE538130C2 - A testing device for wireless power transfer, and an associated method

Info

Publication number: SE538130C2
Application number: SE1451306A
Authority: SE
Inventors: Magnus Wikstrand
Original assignee: Nok9 Ab
Priority date: 2014-11-03
Filing date: 2014-11-03
Publication date: 2016-03-15
Also published as: SE1451306A1

Abstract

16 ABSTRACT A testing device (3 0) is provided for use with a wireless power transmitter device (20) having a wireless power transmitter coil (24). The testing device (30) has ahousing (50), the housing having a bottom side (53) adapted for placement on a surface(25) of the wireless power transmitter device (20), and a top side (54) opposite to thebottom side (53). A wireless power receiver coil (34) is provided in the housing, as wellas therrno sensory means (3 l). The testing device (30) also has an interface (33) toprovide measurement data from the therrno sensory means (3 l). The therrno sensorymeans (3 l) includes at least a first temperature sensor (55) adapted to measure atemperature at a first position inside the housing (5 0), and a heat flux sensor (5 7) adapted to measure a heat ﬂow in the testing device (3 0). Elected for publication: Fig 2

Description

538 1 A TESTING DEVICE FOR WIRELESS POWER TRANSFER, AND AN ASSOCIATED METHOD Technical Field The present invention generally relates to the field of wireless power transfer, and more specifically to wireless power transfer for mobile devices. Even more specifically, the present invention relates to a testing device for use with a wireless power transmitter device having a wireless power transmitter coil. The present invention also relates to a method of emulating the thermal exposure of a mobile device when 10 being subjected to wireless power transfer from a wireless power transmitter device having a wireless power transmitter coil.

Background Wireless power transfer is expected to become increasingly popular, for instance for wireless battery charging of mobile devices such as, for instance, mobile terminals, tablet computers, laptop computers, cameras, audio players, rechargeable toothbrushes, wireless headsets, as well as various other consumer products and appliances.

The Wireless Power Consortium has developed a wireless power transfer 20 standard known as Qi. Other known wireless power transfer approaches include Alliance for Wireless Power, and Power Matters Alliance.

The wireless power transfer standard known as Qi by the Wireless Power Consortium will be referred to, without limitation, throughout this document as the presently preferred wireless power transfer manner applicable to the present invention.

However, the invention may generally be applied also to other wireless power transfer standards or approaches, including but not limited to the ones mentioned above. Operation of devices that comply with Qi relies on magnetic induction between planar coils. Two kinds of devices are involved, namely devices that provide wireless power (referred to as base stations), and devices that consume wireless power (referred to as mobile devices). Power transfer takes place from a base station to a mobile device.

For this purpose, a base station contains a subsystem (a power transmitter) that comprises a primary coil, whereas a mobile device contains a subsystem (a power receiver) that comprises a secondary coil. In operation, the primary coil and the secondary coil will constitute the two halves of a coreless resonant transformer. 1 538 1 Typically, a base station has a flat surface, on top of which a user can place one or more mobile devices so as to enjoy wireless battery charging or operational power supply for the mobile device(s) placed on the base station.

During operation, the power transmitter in the base station will generate heat that will be conveyed from the base station to the mobile device. Moreover, heat will be generated by magnetic induction in the secondary coil of the power receiver, i.e. in the mobile device itself If the combined heat exposure for the mobile device becomes excessive, vital components may be damaged in the mobile device, such as for instance a lithium ion battery or electronic circuitry in a smartphone.

There is therefore a need to test, measure, evaluate, emulate or otherwise assess the thermal exposure of a mobile device when being subjected to wireless power transfer from a wireless power transmitter.

Summary It is an object of the invention to offer improvements in the technical field of wireless power transfer.

One aspect of the present invention is a testing device for use with a wireless power transmitter device having a wireless power transmitter coil. The testing device comprises a housing. The housing has a bottom side adapted for placement on a surface of the wireless power transmitter device, and a top side opposite to the bottom side.

The testing device also comprises a wireless power receiver coil and thermo sensory means provided in the housing, and an interface to provide measurement data from the thermo sensory means. The thermo sensory means comprises at least a first temperature sensor adapted to measure a temperature at a first position inside the 25 housing. The thermo sensory means also comprises a heat flux sensor adapted to measure a heat flow in the testing device. Optionally but preferably, the thermo sensory means further comprises a second temperature sensor adapted to measure a temperature at a second position inside the housing.

As will be apparent from the detailed description of embodiments of this invention, thanks to the provision of theses thermo sensory means, such a testing device may be beneficially used to test, measure, evaluate, emulate or otherwise assess the thermal exposure of a mobile device when being subjected to wireless power transfer from a wireless power transmitter device having a wireless power transmitter coil. For instance, the first temperature sensor may advantageously be positioned 35 near or at the bottom side of the housing and be adapted to provide measurement data 2 538 1 indicative of a temperature related to heat conveyed from the wireless power transmitter device into the testing device.

Correspondingly, the second temperature sensor may advantageously be positioned near or at the top side of the housing and be adapted to provide measurement data indicative of a temperature related to heat generated internally in the testing device and heat dissipated at the top side of the housing.

Furthermore, the heat flux sensor may advantageously be adapted to provide measurement data indicative of the magnitude and direction of a heat flow which results from heat generated by the wireless power transmitter coil of the wireless power trans- 10 mitter device and heat generated by the wireless power receiver coil of the testing device.

Another aspect of the present invention is a method of emulating the thermal exposure of a mobile device when being subjected to wireless power transfer from a wireless power transmitter device having a wireless power transmitter coil. According to the method, a testing device is provided which has a wireless power receiver coil matching the wireless power transmitter coil, and which has a housing with thermal absorption and dissipation properties matching a mobile device to be emulated.

According to this method, the wireless power transmitter device is operated during an operational time to generate wireless power to the testing device. At least a first temperature is measured at a first position in the testing device during the operational time. Optionally but preferably, a second temperature is measured at a second position in the testing device during the operational time, wherein the second position is different from the first position.

Moreover, a heat flow is measured in the testing device during the operational 25 time. Measurement data from the measuring of the first temperature (and the second temperature, if applicable) and the measuring of the heat flow during the operational time is then provided to a processing means.

Embodiments of the invention are defined by the appended dependent claims and are further explained in the detailed description section as well as on the drawings.

It should be emphasized that the term "comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps, or components, but does not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof. All terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [element, device, 3 538 1 component, means, step, etc]" are to be interpreted openly as referring to at least one instance of the element, device, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Brief Description of the Drawings Objects, features and advantages of embodiments of the invention will appear from the following detailed description, reference being made to the accompanying drawings.

Fig 1 is a schematic block diagram of a wireless power transmitter device for wireless power transfer to a mobile device.

Fig 2 is a schematic block diagram of a testing device having thermo sensory means for use with a wireless power transmitter device, and a host device for processing of measurement data provided by the testing device.

Fig 3 is an isometric view of a testing device according to one embodiment, placed on a surface of a wireless power transmitter device.

Figs 4 and 5 are isometric exploded views of a testing device according to one embodiment.

Figs 6 and 7 are isometric exploded views of a testing device according to 20 another embodiment.

Figs 8 and 9 are graphs illustrating exemplary measurement data obtainable by the thermo sensory means of the testing device.

Fig 10 is a flowchart diagram of a method of emulating the thermal exposure of a mobile device when being subjected to wireless power transfer from a wireless power transmitter device.

Detailed Description Embodiments of the invention will now be described with reference to the accompanying drawings. The invention may, however, be embodied in many different 30 forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the particular embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention.

In the drawings, like numbers refer to like elements. 4 538 1 Fig 1 illustrates a wireless power transmitter device 20 for wireless power transfer to a mobile device 10. The mobile device may, for instance, be a mobile terminal (e.g. smartphone) 10a, tablet computer 10b (e.g. surfpad), laptop computer 10c, camera, audio player, rechargeable toothbrush, wireless headset, or another kind of consumer product or appliance.

The wireless power transfer will be described as being compliant with the Qi standard by the Wireless Power Consortium; hence, the wireless power transmitter device 20 is a base station in the Qi terminology. However, as already mentioned, the invention is generally applicable also to other wireless power transfer standards or approaches, including but not limited to the ones mentioned in the Background section.

The wireless power transmitter device 20 comprises a wireless power transmitter 22 having a wireless power transmitter coil 24. Correspondingly, the mobile device 10 comprises a wireless power receiver 12 having a wireless power receiver coil 14. In operation, the wireless power transmitter device 20 will transfer power wirelessly 15 to the mobile device 10 by way of magnetic induction 18 via the wireless power transmitter coil 24 and wireless power receiver coil 14.

The power received by the wireless power receiver coil 14 will drive a load 16 in the mobile device 10. Typically, the load 16 may be a rechargeable battery, such as a lithium ion battery; hence, the wireless power transmitter device 20 will act as a 20 wireless power charger for the mobile device 10. In another scenario, the load 16 may be electronic circuitry in the mobile device, wherein the wireless power transmitter device 20 will act as a wireless power supply for the mobile device 10.

As explained in the Background section, during operation, the wireless power transmitter 22 and coil 24 will generate heat that will be conveyed from the wireless power transmitter device 20 to the mobile device 10. Moreover, heat will be generated by magnetic induction in the wireless power receiver coil 14 in the mobile device 10. If the combined heat exposure for the mobile device 10 becomes excessive, vital components may be damaged in the mobile device, such as for instance a rechargeable battery or electronic circuitry. Also, excessive heat exposure for the mobile device may increase the risk for fire or smoke generation.

To this end, a testing device 30 has been provided, embodiments of which are illustrated in Figs 2-7. There is also provided an associated method of emulating the thermal exposure of a mobile device when being subjected to wireless power transfer from a wireless power transmitter device. This method is illustrated in Fig 10. 538 1 Fig 2 is a schematic block diagram which shows a testing device 30 for use with a wireless power transmitter device 20. The wireless power transmitter device 20 has a wireless power transmitter 22 and a wireless power transmitter coil 24, and may be identical to the wireless power transmitter device 20 in Fig 1. As will be described in more detail below, the testing device 30 has a wireless power receiver 32 with a wireless power receiver coil 34 which matches the wireless power transmitter coil of a mobile device (or type of mobile device) to be emulated. Moreover, the testing device 30 has a housing with thermal absorption and dissipation properties matching the mobile device (or type of mobile device) to be emulated.

In operation, the wireless power transmitter device 20 will transfer power wirelessly to the testing device 30 by way of magnetic induction 18 via the wireless power transmitter coil 24 and wireless power receiver coil 34 during an operational time OT of a test session. As a result, heat will be generated as explained above for Fig 1.

To measure the thermal exposure of the testing device 30 caused by the wireless power transfer from the wireless power transmitter device 20, thermal sensory means 31 are provided in the testing device 30. The thermal sensory means 31, which will be described in more detail below, will provide measurement data via an interface 33 to a host device 40, as seen at 35 in Fig 2.

The host device 40 has an interface 41 for receiving the measurement data 20 obtained by the thermal sensory means 31 in the testing device 30. The interfaces 33 and 41 may be of any suitable type, including simple wiring, a serial interface such as USB, a wireless interface such as Bluetooth of WiFi, etc.

The host device 40 also has processing means 42 for processing the measurement data received from the testing device 30. The processing means 42 may comprise a programmable device, such as a microcontroller, central processing unit (CPU), digital signal processor (DSP) or field-programmable gate array (FPGA) with appropriate software and/or firmware, and/or dedicated hardware such as an application-specific integrate circuit (ASIC).

Furthermore, the host device 40 has reporting means 43 for communicating or 30 presenting the measurement processing results obtained by the processing means 42. This may involve presentation of graphical information on a local user interface (e.g. display) of the host device 40, generating of visual and/or audible alarms, or communication of information to an external device, as seen at 45.

The processing means 42 may also control and/or drive the wireless power transmitter device 20 for the purpose of the test session, as seen at 44. 6 538 1 A suitable load 36 may be provided to handle excess power received by the wireless power receiver coil 34 in the testing device 30. For instance, a suitably dimensioned resistor may be used.

Embodiments of the testing device 30 will now be described with reference to Figs 3-7. Figs 4-5 illustrate a first embodiment, whereas Figs 6-7 illustrate a second embodiment which is similar or even identical to the first embodiment except for the location of one element of the thermal sensory means 31. Fig 3 is common to both embodiments. Other embodiments than the illustrated ones are possible within the scope of the invention.

As seen particularly in Fig 3, the testing device 30 has essentially the shape of a thin box with rounded edges and corners. The disclosed embodiment serves to emulate a mobile device in the form of a smartphone; hence the testing device 30 has the familiar smartphone shape. The testing device 30 has a sandwich design with the footprint dimensions 130 mm x 70 mm in the disclosed embodiment. The sandwich design includes a housing 50 having a lower housing part 51, an intermediate housing part 60 and an upper housing part 52.

The lower housing part 51 has a bottom side 53 adapted for placement on a surface 25 of the wireless power transmitter device 20. The upper housing part 52 has a top side 54 opposite to the bottom side 53. The lower housing part 51 is made of plastic or another material suitable for admitting inductive coupling 18 between the wireless power transmitter coil 24 of the wireless power transmitter device 20 and the wireless power receiver coil 34 of the wireless power receiver 32.

The intermediate housing part 60 is made of plastic or another material suitable for providing sufficient stability to the sandwich design.

The upper housing part 52 is made of a material having heat dissipation properties similar to a typical mobile device that the wireless power transmitter device 20 is designed for use with. Advantageously, the upper housing part 52 may comprise aluminium, glass or a combination thereof.

In the disclosed embodiment of Fig 3, the wireless power transmitter device 20 30 has a cable 44a, which may be connected to the host device 40, as indicated at 44 in Fig 2. The testing device 30 has a cable 35a which may be part of the interface 33 to the host device 40, as indicated at 35 in Fig 2.

Reference is now made to the exploded isometric views in Figs 4 and 5, illustrating the first embodiment of the testing device 30 as viewed from one of its longitudinal sides and one of its lateral sides, respectively. The intermediate housing 7 538 1 part 60 has been removed from the views in Figs 4 and 5 (and in Figs 6 and 7) for enhanced clarity.

The testing device 30 has a sandwich design also internally, as appears from Figs 4 and 5. The wireless power receiver coil 34 is provided in the housing 50 as one of the layers of the sandwich design. Immediately above the wireless power receiver coil 34, a ferrite layer 58 is provided.

A heat flux sensor 57 is adapted to measure a heat flow in the testing device 30. In the disclosed embodiment, the heat flux sensor 57 is positioned between the wireless power receiver coil 34 and the bottom side 53 of the housing 50, and more specifically immediately below the wireless power receiver coil 34.

Below the wireless power receiver coil 34, a first temperature sensor 55 is provided which is part of the thermo sensory means 31. The first temperature sensor 55 is adapted to measure a temperature at a first position inside the housing 50. More specifically, the first temperature sensor 55 is positioned between the wireless power receiver coil 34 and the bottom side 53 of the housing 50. Even more specifically, in the disclosed embodiment of Figs 4 and 5, the first temperature sensor 55 is positioned below the heat flux sensor 57. In the disclosed embodiment of Figs 6 and 7, the first temperature sensor 55 is instead positioned next to the heat flux sensor 57, i.e. in the same layer as the heat flux sensor 57. Other than this difference, the embodiments of Figs 4 and 5, and Figs 6 and 7, are identical.

In the disclosed embodiments, the thermo sensory means 31 further comprises a second temperature sensor 56 adapted to measure a temperature at a second position inside the housing 50. More specifically, the second temperature sensor 56 is positioned between the wireless power receiver coil 34 and the top side 54 of the housing 50. Even more specifically, the second temperature sensor 56 is mounted on the lateral edge of a socket 59 which protrudes from the inner surface of the top side 54 of the housing 50. The socket 59 also serves as mount for the ferrite layer 58.

The particulars, functions and purposes of the first temperature sensor 55, the second temperature sensor 56 and the heat flux sensor 57 will now be described.

As seen in Figs 4-7, the first temperature sensor 55 is positioned near or at the bottom side 53 of the housing 50. The first temperature sensor 55 is adapted to provide measurement data indicative of a temperature related to heat conveyed from the wireless power transmitter device 20 into the testing device 30. As a result, therefore, the first temperature sensor 55 will serve to assess the thermal environment at the bottom of the 8 538 1 emulated mobile device, i.e. nearest the wireless power transmitter device 20, as it is experienced by the testing device 30 during the operational time OT of the test session. The second temperature sensor 56 is positioned near or at the top side 54 of the housing 50. The second temperature sensor 56 is adapted to provide measurement data indicative of a temperature related to heat generated internally in the testing device 30, i.e. by the magnetic induction in the wireless power receiver coil 34. This temperature will also be related to heat dissipated at the top side 54 of the housing 50. As a result, therefore, the second temperature sensor 56 will serve to assess the thermal environment which the internal elements of the emulated mobile device will be exposed to, as it is experienced by the testing device 30 during the operational time OT of the test session.

The duration OT of the test session will be set to an appropriate value which reflects a typical duration of a wireless power transfer session for the emulated mobile device, for instance 60 minutes when the emulated mobile device is a mobile terminal and the wireless power transmitter device 20 is a wireless power charger, or for instance 90 minutes, or more generally in time magnitudes between 1 minutes and 3 minutes, without limitation. In some embodiments, the duration OT of the wireless power transfer session is selected or set in view of a desired or obtained temperature stabilization as indicated by the measurement data provided by the first and/or second temperature sensors 55, 56. A criterion for temperature stabilization may for instance be a deviation less than a threshold value, such as 1 °C, between two or more subsequent temperature readings.

In the disclosed embodiments, the first and second temperature sensors 55, 56 are thermocouples, such as thermocouples type K which are manufactured by Omega Engineering Limited, One Omega Drive, River Bend Technology Centre, Irlam, 25 Manchester, M44 5BD, United Kingdom. The thermocouples generate small sensor output voltage values which are converted by an associated converter unit into a calibrated temperature value in °C. In other embodiments, other types of temperature sensors may be used, such as for instance thermistors, resistance thermometers or silicon bandgap temperature sensors.

Exemplary graphs resulting from temperature measurements by the first and second temperature sensors 55, 56 are found in Fig 8. The upper graph 81 represents the measurement data obtained from the first temperature sensor 55 and approaches an end temperature at about 38 °C after an operational time OT = 90 minutes. The lower graph 82 represents the measurement data obtained from the second temperature sensor 56 and 9 538 1 approaches an end temperature at about 32 °C after the operational time OT = 90 minutes.

The heat flux sensor 57 is adapted to provide measurement data indicative of the magnitude and direction of a heat flow which results from heat generated by the wireless power transmitter coil 24 of the wireless power transmitter device 20 and heat generated by the wireless power receiver coil 34 of the testing device 30. The heat flux sensor 57 is a gSKIN® Heat Flux Sensor by greenTEG, Technoparkstr. 1, CH-8005, Zurich, Switzerland in the disclosed embodiment and has an associated converter unit which converts a small sensor output voltage value into a calibrated W/m2 heat flux 10 value. An exemplary graph 91 resulting from heat flux measurements by the heat flux sensor 57 is found in Fig 9. As is seen in Figs 4-7, in the disclosed embodiments the heat flux sensor 57 is generally located along a first imaginary axis parallel to the bottom and top sides 53, 54 of the housing 50 of the testing device 30, and the direction of the heat flow measured by the heat flux sensor 57 is hence generally along a second imaginary axis being orthogonal or normal to the first imaginary axis.

The heat flux sensor 57 makes it possible to assess not only the magnitude of the resulting heat flow in the testing device 30 (and therefore the emulated mobile device), but importantly also the direction of this heat flow. A positive heat flux value will indicate that more heat originates from the wireless power transmitter device 20 than from the testing device 30 (and the emulated mobile device) itself, whereas a negative value will indicate the opposite — or vice versa.

The aggregated measurement data provided by the first and second temperature sensors 55, 56 and the heat flux sensor 57 will allow the processing means 42 to make various analyses of the (emulated) thermal exposure of a mobile device when being subjected to wireless power transfer from a wireless power transmitter device. The results of such analyses may, for instance, be beneficially used by any or all of the following interest groups: Developers or manufacturers of mobile devices, Developers or manufacturers of wireless power transmitter devices, • Test or compliance entities in the field of wireless power transfer, Test or compliance entities in the field of consumer product safety. Some examples of measurement data are given in the following Table 1. The measurement data was the result of exposing the testing device 30 to respective wireless power charging sessions using seven different wireless power chargers. 538 1 Charger Start temp End-Temp ;charger surfat:e End Temp top sur oe Start heatFlue End Heat ETC ETCS Diff ETTS DUI 23,34 32 414,8, 8 25,3 38,4 31,2 180 1.,,. , ..., 6, C 25, .34,4 32 -370 9,4 7 D 25,8 38,7 34,, 812,9 4,7 E 23,44,33,3 421 9,4 F 3632,8411,7,8 0 39 33,3 414 8,3 Table 1 Here, the first column represents the seven different chargers which were used. The second column is the start temperature in the testing device 30 before the charging starts (uniform temperature within the testing device 30).

The third column is the end temperature measured by the first temperature sensor 55, whereas the fourth column is the end temperature measured by the second temperature sensor 56. As can be seen particularly for chargers C and E, there are a considerable difference in heat generating from different chargers.

The fifth and sixth columns represent the start and end measurement values from the heat flux sensor 57. As can be seen for charges C, E and G, a reversed heat flux direction can be detected during the early part of the charging session.

The seventh and eighth columns represent the temperature differences between beginning and end of charging, as detected by the first and second temperature sensors 55, 56, respectively.

In an alternative embodiment, the testing device 30 only has a single temperature sensor, In this alternative embodiment, the single temperature sensor is positioned and has the same function as the first temperature sensor 55 described above. In yet an alternative embodiment, the single temperature sensor is positioned and has 20 the same function as the second temperature sensor 56 described above.

Fig 10 is a flowchart diagram of a method of emulating the thermal exposure of a mobile device when being subjected to wireless power transfer from a wireless power transmitter device 20 having a wireless power transmitter coil 24. The method involves the following.

In a first step 110, a testing device is provided which has a wireless power receiver coil matching the wireless power transmitter coil 24 and which has a housing with thermal absorption and dissipation properties matching a mobile device to be emulated. The testing device may advantageously be the testing device 30 as described above for Figs 2-9.

In a second step 120, the wireless power transmitter device 20 is operated during an operational time OT to generate wireless power to the testing device 30. 11 538 1 In a third step 130, at least a first temperature T1 is measured at a first position in the testing device 30 during the operational time OT.

In a fourth step 135 which is optional but preferred, a second temperature T2 is measured at a second position in the testing device 30 during the operational time OT.

In a fifth step 140, a heat flow is measured in the testing device 30 during the operational time OT.

In a sixth step 150, measurement data is provided from the measuring of the first temperature and the measuring of the heat flow during the operational time OT to a processing means, for instance the processing means 42 in the host device 40 in Fig 2.

This method may have any or all of the same or functionally corresponding features as the testing device 30 described above for Figs 2-9. For instance, the first position is preferably near or at a bottom side 53 of the housing 50 of the testing device 30, the measuring of the first temperature T1 being indicative of a temperature related to heat conveyed from the wireless power transmitter device 20 into the testing device 30.

The second position is preferably near or at a top side 54 of the housing 50 of the testing device 30, the measuring of the second temperature T2 being indicative of a temperature related to heat generated internally in the testing device 30 and heat dissipated at the top side 54 of the housing 50.

The measurement data from the measuring of the heat flow is preferably 20 indicative of the magnitude and direction of a resulting heat flow from heat generated by the wireless power transmitter coil 24 of the wireless power transmitter device and heat generated by the wireless power receiver coil 34 of the testing device 30. The invention has been described above in detail with reference to embodiments thereof. However, as is readily understood by those skilled in the art, other embodiments are equally possible within the scope of the present invention, as defined by the appended claims. 12

Claims

538 1 CLAIMS

1. A testing device (30) for use with a wireless power transmitter device (20) having a wireless power transmitter coil (24), the testing device comprising: a housing (50), the housing having a bottom side (53) adapted for placement on a surface (25) of the wireless power transmitter device (20), and a top side (54) opposite to the bottom side (53); a wireless power receiver coil (34) provided in the housing; thermo sensory means (31) provided in the housing; and an interface (33) to provide measurement data from the thermo sensory means (31), wherein the thermo sensory means (31) comprises: at least a first temperature sensor (55) adapted to measure a temperature at a first position inside the housing (50); and a heat flux sensor (57) adapted to measure a heat flow in the testing device (30).

2. The testing device as defined in claim 1, wherein the first temperature sensor (55) is positioned between the wireless power receiver coil (34) and the bottom side (53) of the housing (50).

3. The testing device as defined in claim 1 or 2, wherein the heat flux sensor (57) is positioned between the wireless power receiver coil (34) and the bottom side (53) of the housing (50).

4. The testing device as defined in any preceding claim, wherein the thermo sensory means (31) further comprises a second temperature sensor (56) adapted to measure a temperature at a second position inside the housing (50).

5. The testing device as defined in claim 4, wherein the second temperature sensor (56) is positioned between the wireless power receiver coil (34) and the top side (54).

6. The testing device as defined in any preceding claim, the housing (50) having a lower housing part (51) comprising said bottom side (53), and an upper 13 538 1 housing part (52) comprising said top side (54), wherein the upper housing part (52) is made of a material having heat dissipation properties similar to a typical mobile device (10) that the wireless power transmitter device (20) is designed for use with.

7. The testing device as defined in claim 6, wherein the upper housing part (52) comprises at least one of aluminium and glass.

8. The testing device as defined in any of claims 4-7, wherein: the first temperature sensor (55) is positioned near or at the bottom side (53) of 10 the housing (50) and is adapted to provide measurement data indicative of a temperature related to heat conveyed from the wireless power transmitter device (20) into the testing device (30); the second temperature sensor (56) is positioned near or at the top side (54) of the housing (50) and is adapted to provide measurement data indicative of a temperature related to heat generated internally in the testing device (30) and heat dissipated at the top side (54) of the housing (50); and the heat flux sensor is adapted to provide measurement data indicative of the magnitude and direction of a heat flow which results from heat generated by the wireless power transmitter coil (24) of the wireless power transmitter device (20) and heat generated by the wireless power receiver coil (34) of the testing device.

9. The testing device as defined in claim 1, wherein the first temperature sensor (55) is positioned between the wireless power receiver coil (34) and the top side (54) of the housing (50).

10. The testing device as defined in any preceding claim, wherein the testing device is adapted for use with a wireless power transmitter device (20) in the form of a wireless charger (20).

11. A method of emulating the thermal exposure of a mobile device when being subjected to wireless power transfer from a wireless power transmitter device (20) having a wireless power transmitter coil (24), the method involving: providing (110) a testing device (30) having a wireless power receiver coil (34) matching the wireless power transmitter coil (24) and having a housing (50) with thermal absorption and dissipation properties matching a mobile device to be emulated; 14 538 1 operating (120) the wireless power transmitter device (20) during an operational time (OT) to generate wireless power to the testing device (30); measuring (130) at least a first temperature (Ti) at a first position in the testing device (30) during the operational time (OT); measuring (140) a heat flow in the testing device (30) during the operational time (OT); and providing (150) measurement data from the measuring of the first temperature and the measuring of the heat flow during the operational time (OT) to a processing means (42).

12. The method as defined in claim 11, further involving: measuring (135) a second temperature (T2) at a second position in the testing device (30) during the operational time (OT), the second position being different from the first position.

13. The method as defined in claim 12, wherein: the first position is near or at a bottom side (53) of the housing (50) of the testing device (30), the measuring of the first temperature (Ti) being indicative of a temperature related to heat conveyed from the wireless power transmitter device (20) into the testing device (30); the second position is near or at a top side (54) of the housing (50) of the testing device (30), the measuring of the second temperature (T2) being indicative of a temperature related to heat generated internally in the testing device (30) and heat dissipated at the top side (54) of the housing (50); and the measurement data from the measuring of the heat flow is indicative of the magnitude and direction of a resulting heat flow from heat generated by the wireless power transmitter coil (24) of the wireless power transmitter device (20) and heat generated by the wireless power receiver coil (34) of the testing device (30). 538 1 I foljande bilaga finns en oversattning av patentkraven till svenska. Observera att det r patentkravens lydelse pa engelska som gaiter. A Swedish translation of the patent claims is enclosed. Please note that only the English claims have legal effect.